Endoscopic ultrasound-guided fine-needle aspiration can differentiate between tuberculosis and sarcoidosis

 

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It is very difficult to make a differential diagnosis between tuberculosis and sarcoidosis by considering only mediastinal lymph nodes, as these two diseases often have a high degree of overlapping clinical and diagnostic features. The article by Fritscher-Ravens et al. [1] provided some answers to this challenge. As a prospective study, the design of this investigation was rigorous and the conclusion should be credible. There are some reports of the use of endoscopic ultrasonography-guided fine-needle aspiration (EUS – FNA) in the differential diagnosis of mediastinal lymphadenopathy but most are retrospective studies [2] [3]. We have also performed mediastinal lymph node puncture and believe that EUS – FNA is a safe, minimally invasive, and effective diagnostic method. In the Fritscher-Ravens article, the authors used EUS to guide the endoscope and detect pathological lymph nodes and then used FNA to obtain tissue for cytological and bacteriological analysis. From their precise work, the following positive results were obtained. First, on EUS the node of tuberculosis was significantly smaller than that of sarcoidosis. Second, after biopsy tissue staining with May – Grünwald – Giemsa, cytology revealed epithelioid cell granulomas on a “dirty background” with debris suggesting tuberculosis; a “clear background” was suggestive of sarcoidosis. Third, the sensitivity of cultures from the FNA samples for Mycobacterium tuberculosis was 71 % (95 %CI 0.53 – 0.85). Therefore, follow-up and the typical clinical features of tuberculosis contributed to the final diagnosis.

The results were fully analyzed and discussed in detail by the authors. However, we think that some other aspects also need to be considered. First, as a prospective study, approval from the medical ethics committee should be stated. Second, results from “clinical follow-up” or positive bacteriological culture was used as the gold standard for the diagnosis of tuberculosis, and simple cytopathological diagnosis was used as the standard for sarcoidosis; in fact, the Kveim test is also helpful in the diagnosis of sarcoidosis.

• References

• 1 Fritscher-Ravens A, Ghanbari A, Topalidis T et al. Granulomatous mediastinal adenopathy: can endoscopic ultrasound-guided fine-needle aspiration differentiate between tuberculosis and sarcoidosis. Endoscopy 2011; 43: 955-961
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• 2 Khoo KL, Ho KY, Khor CJ et al. First endoscopic procedure for diagnosis and staging of mediastinal lymphadenopathy. World J Gastroenterol 2009; 15: 6096-6101
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• 3 Berger LP, Scheffer RC, Weusten BL et al. The additional value of EUS-guided Tru-cut biopsy to EUS-guided FNA in patients with mediastinal lesions. Gastrointest Endosc 2009; 69: 1045-1051
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